Spain is famous for its weather, Benidorm, Spanish food, it's football team, Barcelona, and basically being a rather sunny place overall â none of these descriptions are incorrect, and in fact they are all entirely true!
As the temperature of the air increases its density decreases. Therefore the thrust produced by the engine decreases. As the air pressure increases, its density increases, causing thrust produced by the engine to increase. Altitude has a double effect on thrust. As the altitude increases, the air becomes colder and denser, up to the beginning of stratosphere. This causes the thrust to increase.
If the atmosphere is unstable, any parcel of air that is lifted will tend to rise like a hot air balloon. As this parcel rises, it decreases in temperature at a rate of 5-1/2Â° per 1,000 feet, and will continue to rise until it reaches a level in which its new temperature equals that of the surrounding air.